One firmare version in the devices the driver takes care of is
completely broken and needs periodic pokes from our side. We
implemented this as a periodic delayed queue. The idea of the pokes
was taken from the suse enterprise kernel, in particular from Libor's
"Elo touchscreen firmware M workaround".

I am quoting him here:
  This patch adds periodic polling of the Elo USB touchscreens. Needed
  as a workaround for devices with M-level firmware, otherwise these
  devices are known to misbehave (as reported by Elo developers).
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Tested-by: NPetr Ostadal <postadal@suse.cz>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: Vojtech Pavlik <vojtech@suse.cz>
Cc: Egbert Eich <eich@suse.com>
Cc: Libor Pechacek <lpechacek@suse.cz>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

This is a driver for ELO 4000/4500 devices which report themselves as
HID devices, but do not really send HID events on touch. So we
introduce a new HID 'quirk' driver with a raw_event handler where we
take care of those events.

What we need additionally is an input_configured hook, because the
device does not mention anything about PRESSURE and TOUCH in its
report descriptor, but it actually generate those. So we set the bits
in the corresponding input_dev in that hook.

Thanks to Petr Ostadal who was willing to test the driver. The rest of
Cc's listed below had something to do with that driver over the years
in our enterprise tree.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Tested-by: NPetr Ostadal <postadal@suse.cz>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: Vojtech Pavlik <vojtech@suse.cz>
Cc: Egbert Eich <eich@suse.com>
Cc: Libor Pechacek <lpechacek@suse.cz>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>